Having said that, it appears that Chromium runs pretty smoothly on VirtualBox. If you're interested in trying it out yourself, that appears to be the best way to go.
The whole preview (and linked image gallery) makes interesting reading, although Serdar offers a few key conclusions that are worth the price of admission. For starters, he observes that it is already quite clear how Google wants to position Chrome in relation to other desktop OSes: The first thing that's clear is how Google is forcibly distinguishing Chrome OS from a conventional desktop operating system, for better or worse. This is not and probably never will be a replacement for a desktop, but an adjunct -- in the same way that, for instance, that the iPhone is not a replacement for a full-blown Mac desktop, but a complement to it. (Chrome OS is only meant to run on Google-approved devices, so the parallel to the iPhone has more than one dimension.) He also points out the biggest question mark at this point: How Chrome will handle offline access, as opposed to serving simply as a glorified access point for cloud-based applications: It's not clear whether that's going to be handled by things in the base package, or by components which are primarily Google-branded, and not available as Chromium OS (as opposed to Chrome OS) pieces. Right now little, if any, of this plumbing exists, and that alone is a good reflection of the very alpha state of the system. If Google leaves too many of the key parts of the Chrome OS experience to be filled in by its nascent developer community, that will clash badly with its plans for delivering a solid end-user experience. In other words, Chromium still offers curious techies far more questions than answers. But even this early in the game, it appears that Google is laying the groundwork for what could be a significant new force in the desktop OS market.